There are a wide variety of shooting rests, bags, and pads available for supporting the forearm of a rifle (or shotgun). Many of these include deformable bags filled with displaceable material, such as sand, beans, or beads, such that it can conform to the shape of the surface on which it is resting and to the position of the forearm. In some embodiments, the amount of fill material may be varied to adjust the firmness of the conformable unit. Because the circumstances under which a shot in the field (or in competition) is to be taken may vary greatly, a shooter may need to have support bags in a variety of sizes and shapes.
Typically, a sand bag type rest is used elevate and/or position the barrel or forearm of the firearm and the bag is kept in position simply by gravity or by pressure applied against it by the shooter. Other rests may include some device for holding it in place, such as a magnet, clamp, or friction material. In some cases, a conformable shooting support may be attachable to the rifle forearm or barrel. However, the available products do not allow interchangeability of size and/or shape of the rest, other than to exchange the entire device for a different one, and a long or large bag attached to the forearm at one point may sag or droop when lifted.